environment: Allow setting environment variables with -E.

* guix/scripts/environment.scm (show-environment-options-help) [-E]: Document
the change.
* guix/scripts/environment.scm (%options) [-E]: If arg contains =, split it
and store under 'extra-env.
* guix/scripts/environment.scm (launch-environment, launch-environment/fork)
(launch-environment/container): Take and use `environment-variables' keyword argument.
* guix/scripts/environment.scm (guix-environment*): Process 'environment-variables opts.
* guix/profiles.scm (load-profile): Add `environment-variables' keyword argument.
* doc/guix.texi (Invoking guix shell): Document the change.
* tests/guix-environment.sh (GUIX_TEST_ZZZ): Test it.

Change-Id: Ib1db19ef73dda8f561b05731079a96eda076e365
Signed-off-by: Maxim Cournoyer <maxim@guixotic.coop>
Modified-by: Maxim Cournoyer <maxim@guixotic.coop>

1 files changed, 4 insertions, 1 deletions

diff --git a/tests/guix-environment.sh b/tests/guix-environment.sh
index 56cb289f2ff..450f0265221 100644
--- a/tests/guix-environment.sh
+++ b/tests/guix-environment.sh
@@ -49,18 +49,21 @@ test -x `sed -r 's/^export PATH="(.*)"/\1/' "$tmpdir/a"`/guile
 
 cmp "$tmpdir/a" "$tmpdir/b"
 
-# Check '--preserve'.
+# Check '--preserve', as well as its -E VAR=VALUE special case.
 GUIX_TEST_ABC=1
 GUIX_TEST_DEF=2
 GUIX_TEST_XYZ=3
+GUIX_TEST_ZZZ=4
 export GUIX_TEST_ABC GUIX_TEST_DEF GUIX_TEST_XYZ
 guix environment --bootstrap --ad-hoc guile-bootstrap --pure    \
      --preserve='^GUIX_TEST_A' --preserve='^GUIX_TEST_D'        \
+     --preserve='^GUIX_TEST_Z' -E 'GUIX_TEST_ZZZ=overridden'    \
      -- "$SHELL" -c set > "$tmpdir/a"
 grep '^PATH=' "$tmpdir/a"
 grep '^GUIX_TEST_ABC=1' "$tmpdir/a"
 grep '^GUIX_TEST_DEF=2' "$tmpdir/a"
 grep '^GUIX_TEST_XYZ=3' "$tmpdir/a" && false
+grep '^GUIX_TEST_ZZZ=overridden' "$tmpdir/a"
 
 # Make sure the exit value is preserved.
 if guix environment --bootstrap --ad-hoc guile-bootstrap --pure \